<p>I have tried to find more information on this aswell, as well, thinking it could've been someone related to the order.</p><p>I did not find anything else though, and from this line in the quest:<br>Evrard the Miller: There's a passphrase: YSELDA. Remember that. Now go and the best of luck to you, traveller!<br>Evrard the Miller <a rel="nofollow" href="https://tibia.fandom.com/wiki/The_Order_of_the_Lion_Quest#Evrard_the_Miller_2">(quest transcripts in Tibia wikia)</a> gives the name YSELDA just as a passphrase and nothing else, and during the quest advancements all the NPCs you listed react as if it is a passphrase.</p><p>The reactions you posted, I interpret just as distractions, and are much different than the ones during the quest. I think Yselda doesn't exist herself but I also hope I'm proven wrong.</p>